1. Field of the Invention
The present invention relates to a silver-colored sintered product used for ornamental articles, tools, sliding members, blades for industrial use, stamps, spectacle frames, tablewares, and sporting goods such as pins of shoes, golf clubs, etc. and to a method of producing the same. In particular, the invention relates to a silver-colored sintered product having large strength, high hardness, resistance against chipping, excellent resistance against corrosion and excellent ornamental property that can be used as ornamental materials such as frames for timepieces, necktie pins, bracelets, pierced earrings, earrings, and fishing goods, and to a method of producing the same.
2. Description of the Prior Art
Ornamental parts such as armoring parts for timepieces and the like must have good corrosion resistance, increased resistance against scratching, and long-lasting metallic luster. As materials having metallic luster that are best suited for use as ornamental parts, there have been used a stainless steel and carbides of metals such as sintered alloys obtained by bonding WC and TiC with such metals as Ni and Co.
The stainless steel has an excellent corrosion resistance but has a low hardness and is subject to be scratched. The sintered alloys comprising chiefly WC and TiC and bonded with metal elements such as Ni and Co, have no problem in regard to the hardness but have a low corrosion resistance against the human sweat and sea water.
In recent years, TiB.sub.2 sintered products which are borides of titanium having high hardness and excellent corrosion resistance have been developed and placed in practical use (see, for example, Japanese Laid-Open Patent Publication No. 27975/1983, Japanese Patent Publication No. 18458/1984, Japanese Laid-Open Patent Publications Nos. 270265/1986 and 294739/1993).
These TiB.sub.2 sintered products have a flexural strength of from 800 to 1000 MPa, Vickers' hardness of from 18 to 24 GPa, fracture toughness of from 4 to 7 MPa.multidot.m.sup.1/2 and excellent corrosion strength.
However, the above-mentioned TiB.sub.2 sintered products must be sintered at a temperature of as high as from 1600 to 2000.degree. C.; i.e., sinterability is poor.